The present invention relates to a structure for preventing an axial leakage in a scroll compressor, and more particularly to a structure for preventing a fixed scroll from rotating on its own axis or swinging in a radial direction.
As shown in FIGS. 1 and 2, a conventional scroll compressor includes (a) a stator 2 mounted in a housing 1, (b) a rotor 3 rotated by a magnetic force of the stator 2 and fixed to a crankshaft 4, (c) an orbiting scroll 12 fixed to the upper end of the crankshaft 4, (d) a fixed scroll 13, facing the upper surface of the orbiting scroll 12, attached to a main frame 14 by bolted leaf springs 8, (e) a discharge hole 11 through which a high pressure refrigerant is discharged from a compression chamber 9 formed between the orbiting scroll 12 and the fixed scroll 13, and (f) a discharge chamber 10 holding the refrigerant which is discharged through the discharge hole 11. The fixed scroll 13 includes a back pressure chamber 7 with a uniform cross section at its top side, and a back pressure hole 6 which emits a portion of the refrigerant in the process of compression.
In the foregoing, when the stator 2 is activated, the rotor 3 and the crankshaft 4 rotate, thereby rotating the orbiting scroll 12. Accordingly, the refrigerant which is drawn through a suction pipe 5 is discharged through the discharge hole 11 to the discharge chamber 10, by the pressure of the compression chamber 9. Generally, the crankshaft 4 rotates about 2 to 3 times during the suction and discharge process of the refrigerant.
As the above, when the refrigerant drawn from the suction pipe 5 is compressed, there are two different types of refrigerant leakage, from a high pressure pocket to a low pressure pocket. The first type is called an axial leakage, where there is leakage into gaps between the tips of scroll wraps and the bottom of opposing scroll. The second type is called a radial leakage, where there is leakage into gaps between opposing scroll wraps.
As described above, to prevent the axial leakage, the next structure is provided. The fixed scroll 13 is fixed to the main frame 14 by bolted leaf springs 8, the back pressure chamber 7 with a uniform cross section is formed at the top side of the fixed scroll 13, and a portion of the refrigerant in the process of compression is emitted into the back pressure chamber 7 through the back pressure hole 6, thereby the pressure of the back pressure chamber 7 becomes constant. The, the fixed scroll 13 moves downward by the back pressure applied to the fixed scroll 13, thereby the gaps between the tips of scroll wraps and the bottom of opposing scroll are minimized, thus the axial leakage is minimized.
However, because the axial leakage is prevented by the pressure of the back pressure chamber 7, a power loss occurs, as shown in FIG. 3. In FIG. 3, an area S depicts the power loss due to compression chamber communicating with the back pressure hole.
Since the fixed scroll 13 is fixed to the main frame 14 by the leaf springs 8, the design of the leaf springs 8 becomes complicated. Also, the assembly process becomes complicated because there are numerous parts.